Dispersing and grinding apparatus and method of dispersing and grinding paste



May 17, 1966 c. E. CRAIG 3,251,578

DTsPERsING AND GRINDING APPARATUS AND METHOD 0F DTsPERsING AND @BINDING PASTE Filed June 15, 1961 5 Shams-Shea*l 1 35am PM May 17, 1966 DISPERSING AND GRINDING APIARATUS AND METHOD OF DISP Filed June l c E. CRAIG 3,251,578

ERSING AND GRINDING PASTE 5 Sheets-Sheet 2 /il lIll/ May 17, 1966 c. E. CRAIG 3,251,578

DISPERSING AND GRINDING APPARATUS AND METHOD OF DISPERSING AND GRINDING PASTE Filed June 15, 1961 5 Sheets-Sheet 5 United States Patent O This invention relates to a dispersing and grinding 4apparatus for and method of dispersing and grinding paste, in-which .paste is dispersed and some of -the pigment particles m-ay be ground by a suitable dispersing media, such as sand, for example, by rotation of" a tubular agitator in a stationary container to move a mixture of paste and dispersing media between two adjacent surfaces of the agitator and the container.

l When the paste aggregates are dispersed some of theV pigment particles may be ground by the action of the dispersing media. Whatever grinding action takes place .in the process hereinafter described is incidental to the dispersing process. The complete action will be referred to las a dispersing action, but it will be understood that the term dispersing shall be interpreted to include anygrinding of the pigment particles that may occur.

The upper and lower edges of the tubular agitator are respectively spaced from the top and bottom of the container. The top of the container is provided with an opening registering with the interior of the tubular agitator. The dispersing media is inserted into the apparatus through the opening in the top of the container and falls through the tubular agitator to the bottom of the container. The paste to be dispersed is then fed in :a continuous stream through the opening in the top of the container to mix with the dispersing media. The paste, from which paint is made, comprises pigment stabilized with resin and having sufficient thinner to provide suitable ow. The tubular agitator is rotated, and centrifugal force throws the mixture of dispersing media and paste outwardly under the lower edge of the agitator and against the inner surface of the vertical wall of the container. As centrifugal force throws themixture outwardly, the mixture moves upwardly through an annular mixing zone, i.e. the space between the outer vertical surface of the .agitator and the inner vertical surface of the container, .toward a screened outlet adjacent the top of the container.

During the movement of the mixture upwardly through the mixing zone, the mixing -action of the dispersing media disperses and sometimes grinds the aggregates of paste. The paste is in fluid condition at the time the mixture reaches the screen level. At the screen level centrifugal force causes the paste to iiow outwardly through ythe screen. The screen retains the dispersing media, and the dispersing medi-a that is screened out of the mixture is movedupwardly by the pressure of additional mixture of dispersing medi-a and paste being moved upwardly through the mixing zone. The dispersing media that is screened out of the mixture is forced inwardly over the upper edge of Ithe tubular agitator and falls downwardly to the bottom of the unit by gravity. Fresh undispersed paste being continuously fed through the opening in the top of the container also falls to the bottom of the unit by gravity and is mixed with the previously used dispersing media to complete the `cycle of continuous operation.

The dispersing medi-a, which also may grind the paste, may range in size from 3 to 60 mesh, but a mesh size between 16 and 20 is preferred. As herein referred to, the mesh size is based upon U.S. Sieve Series, A.S.T.M. specifications. The dispersing media may be sand, metal ice particles, steel balls, or glass or plastic beads of corresponding size. The dispersing medi-a should be durable and should be capable of retaining its particle size over a prolonged period of continuous use. It is also desirable that the dispersing media be inert with respect to the paste being dispersed to avoid discoloration of the paste. This characteristic of inertness -to the paste is not essential in cases where a slight discoloration of the paste is not objectionable.

The ratio of the dispersing media to the paste is yan important factor since it influences the rate of dispersion and screening. Preferably the process is started with half of the mix .as actual solid sand volume. The mix may be adjusted to control dispersion. After the dispersing media is placed in the container the paste is fed into the top of the container and drops to the bottom by gravity. The tubular agitator is then rotated at a surface or peripheral speed of from about 1000 to 5000 feet per minute. A peripheral or surface speed of 2000 to 4000 feet per minute is preferred, depending, to some extent,

upon the visocity of the paste. After the mix is adjusted to provide .the desired rate of dispersion, the ratio of the dispersing media to the paste remains substantially constant. The paste to be dispersed is fed into the top of the container continuously at the same rate as the processed paste ows through the outlet. The outlet comprises an opening adjacent the top of the container that is covered by a screen that may be easily removed for cleaning. The mesh of the screen is fine enough to retain the dispersing media, but allows the processed paste to ow through the screen. A chute or trough leads from the bottom of the screen to a suitable receptacle. A temperature control jacket extends around the outside of the container to control the temperature.

The peripheral surface of the tubular agitator is spaced from the inner surface of the vertical wall of the container to form an annular mixing zone having a height equal to the height of the agitator. The spacing between `the adjacent vertical surfaces of the agitator and container is close enough so that rotation of the agitator mixes the dispersing media with the paste with sucient force to disperse the aggregates of paste. Rotation of the agitator moves the mixture of paste and sand outwardly and upwardly through the mixing zone. The height of the mixing zone must be suiiicient to insure fluidity of the paste when it reaches the level of the outlet. If the distance-between the outer vertical lsurface of the agitator and the inner vertical surface of the container is too great, the action of the sand is not suicient to disperse the paste properly. If the distance between the -outer vertical surface of the agitator and the inner vertical surface of the container is too small, there is too much wear on the surface of the container and screen and the volume of paste being dispersed is reduced.

In the prior art sand grinding apparatus embodying the use of disk-type agitators, the sand tends to migrate or climb upwardly with the paste. The movement of the sand and paste is always upwardly, with the result the concentration of sand is greater at the top of the unit and less at the bottom. The high :sand concentration adjacent the outlet makes the separation of paste and sand more diicult and therefore slows down the process. The reduced concentration of sand at the bottom of the unit causes less dispersion of the paste in that area.

In contradistinction, in applicants novel dispersing and grinding apparatus embodying the use of a tubular agitator, the agitator maintains a su-bstantially uniform ratio ofdispersing media to paste throughout the mixing zone, with the result that the dispersion of the paste is uniform throughout the mixing zone. Since the same dispersing media is used over and over with fresh undispersed paste constantly fed into the unit, it is desirable to use dispersing media that will remain within the desired -size range, that is 16to 20 mesh, throughout the dispersing process.

The greater eciency of the paste dispersion with the tubular agitator, as compared to the disk-type agitator, increases the quantity of paste that can be dispersed per pound of sand. The more effective dispersion by the tubular agitator enables the use of a smaller screen for structures of the same capacity when the tubular agitator is used. The smaller screen is more compact and may be removed `and cleaned easier than a larger screen.

The vertical wall of the agitator is preferably perforated to keep the dispersing media from lbuilding up on the inside of the tubular agitator as dispersing media falling down the inside of the tubular agitator is thrown against the vertical wall of the agitator by centrifugal force. The perforations are spaced throughout the surface of the vertical wall. It is undesirable to have the dispersing media build up on the inside of the tubular agitator becausesuch media does no substantial amount of useful work, reduces the amount of dispersing media in the mixing Zone, and requires more power to rotate the extra Weight. r

The structure by means of which the above mentioned and other advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawings, showing an illustrative embodiment of the invention, in which:

FIGURE l is a top plan View of an apparatus embodying the invention;

FIG. 2 is a side elevational view of the apparatus shown in FIG.-l;

FIG. 3 is a top view, partly in elevation and -partly* in section, showing the container and the agitator;

FIG. 4 is a cross sectional view, taken generally along the line 4-4 of FIG. 3;

FIG. 5 is a cross sectional View, taken along the line 5-5 of FIG. 4;

FIG. 6 is a fragmentary view, partly in elevation and partly in section, showing the cla-mp for securing the screen holder to the container; and

FIG. 7 is a fragmentary View, partly in elevation and partly in section, showing the tubular agitator positioned in the container.

The apparatus -of the present invention comprises a stationary container 2 and an agitator unit 3, hereinafter described, mounted on a rotatable shaft 4. In FIGS. 1 and 2 I have shown means for supporting the apparatus to illustrate the manner in which rit is used. It will be understood that the apparatus may -be supported in any suitable manner, and the supporting means shown is merely exemplary of a suitable structure. The supporting structure does not constitute part of the invention and 4will not be specifically described. The supporting structure illustrated includes an upright jack 5 mounted on a base 6. The jack may be operated by air or ofil. A T-bar 7 is secured to a motor plate assembly 8 and depends therefrom for a purpose hereinafter disclosed. The motor plate assembly 8 supports a motor 9 and a mounting head 10.- A drive assembly 11, protected by a guard 12 is driven by motor 9 and rotates shaft 4.

The means for supporting the stationary container 2 comprises a support member 13 `bolted or otherwise secured to jack 5 and having one end shaped to lit around a portion of the periphery of the container. The ends of support member 13 adjacent container 2 is secured to flanges 14, that project outwardly from the container, by means of bolts 15 or other suitable fastening means. The

other ends of support member 13 are clamped against op-- posite sides of the jack as indicated at 13. The ends of supporting member 13 outside the bolts 13 are spaced to provide -a guideway through which T-bar 7 slides to insure proper alignment of the mechanism as it is moved vertically relative to the support member. A piston 5 fin jack 5 has a travel sufficient to move the mounting head upwardly far enough to lift shaft 4 clear of container 2 when the device is to be cleaned or serviced.

Stationary container 2 comprises a bottom wall 16, an inner vertical Wall 17 and an outer vertical wall 18 forming a temperature control jacket around the container. The temperature control jacket has a suitable inlet 19 and outlet 20, as shown in FIG. 4. A drain opening 21 is disposed in bottom wall 16. A tting 23 having an opening 24 therein is screwed in a coupling 25 surrounding opening 21. A screen 26 is sold-ered to the upper annular edge of fitting 23 and an annular washer 22 is positioned between fitting 23 and bottom wall 16. The opening 24 may be closed by any suitable plug or by a pipe having a valve therein.

After a run is completed, and the apparatus is to be used for dispersing paste of a different oolor, a suitable thinner is added to the paste remaining in the container. The valve is opened or the plug is removed from opening 24, and the mixture of paste' and thinner is allowed to drain through screen 26 and to pass through opening 24 l into a suitable receptacle.

Screen 26 is fine enough to retain the sand in the container.

A small area of the upper edge portion of each of vertical walls 17 and 18 is cut away to provide an outlet adapted to be covered by a screen 27 through which the dispersed paste flows. The portion of the temperature control jacket directly below the screen is provided with a closure member 28 extending between walls 17 and 18 at the upper edges of the cutaway portions. Vertical walls 29 extend upwardly from opposite ends of closure member 28 to close the sides of the temperature control jacket adjacent the edges of screen 27. A chute or trough 30 extends downwardly and outwardly from the outer wall of container 2 below the outlet for the ow of the dispersed paste through the screen to a suitable receptacle.

Screen 27 is secured to a frame or holder comprising side walls 31, a top wall 32 and a bottom wall 33. A handle 34, secured to walls 32 and 33 facilitates manipulation of the screen. The screen holder is held in place by clamps 35 mounted on the outer wall 18 adjacent opposite sides of the outlet and fitting on threaded bolts 36 projecting outwardly from side walls 31. The clamping members are held on bolts 36 by nuts 37. The clamps 3S shown in the drawings are toggle action clamps, but any suitable clamping members may be used.

A top 38, seated on the upper edge of wall 17, iits within the outer Wall 13 and is held in place by clamps 39. The specific type of clamp used is not critical, but the clamps shown in the drawings are pivotally mounted on supports 40 bolted to lugs 41 secured to the outer walls 18 by welding or similar means. Top 38 has an opening 42 through which shaft 4 extends. A sleeve 43 having a diameter equal to the diameter of opening 42 depends from closure plate 38 -at the edges of the opening to keep the dispersing media from the opening.

A tubular agitator 44 is positioned in said container. The agitator comprises a substantially open bottom 45, in the form of a spider secured to the bottom of shaft 4 by a nut 46, and a vertical wall 47. Wall 47 4is preferably provided with a plurality of perforations 48 spaced throughout its area. Wall 47 is spaced a short distance from' the inne-r surface of wall 17. The spacing is important because if wall 47 is spaced too far from wall 17 the mixing action of the dispersing media, hereinafter described, will not be strong enough for the dispersing media to disperse the aggregates of paste, and if the spacing is too close the action of the dispersing media will cause excessive wear on the vertical wall of the agitator, the inner surface of the container wall, and on the screen.

In the operation of the apparatus, the dispersing media and the paste to be dispersed are fed into the container through opening 42 `and drop to the bottom of the container by gravity. The paste is fed continuously and the rate of feed is equal to the rate of outflow of processed paste through the screen 27. The dispersing media ret mains in the container and is not replenished except at long intervals when small amounts thereof have been lost for various reasons. The loss of dispersing media is so small that it will be disregarded in the present discussion.

The amount of dispersing media used may vary slightly, but preferably the solid dispersing media volume is approximately 50% of the 'working mix. The amount of dispersing media may be adjusted to control dispersion and is kept as low as possible-consistent with good results because the paste flow decreases rapidly with increase of volume of dispersing media. Tubular cylinder 44 is rotated continuously within container 2 at a peripheral or surface speed of from about 2000 to 4000 feet per minute, and the 4centrifugal force causes the mixture of dispersing media and paste to move under the lower edge'of-the tubular agitator to the inner surface of the wall 17 of the container and upwardly through the mixing zone.

It has been found that the tubular agitator controls the movement of the dispersing media within the container and maintains a substantially uniform ratio of dispersing media to paste throughout the mixing zone. The constancy of the ratio of thedispersing media to the paste results in more effective screening, i.e., separating the dispersed paste from the dispersing media, and also more effective dispersion than is possible with disk-type agitators. The increased screening efficiency permits a reduction of Screen area to about 20% of the screen area required in grinding units having disk-type agitators.

As the mixture of dispersing media and paste moves upwardly through the mixing zone lit comes into contact with screen 27. The centrifugal force causes the paste to flow through the screen, and the dispersing media that is screened out is pushed upwardly by the upward movement of the mixture of dispersing media and paste below it. Eventually, the dispersing media that is screened out is forced4 over the top of tubular wall 47 and moves t o ward the bottom of the unit. Centrifugal force causes some of the dispersing media moving downwardly into the tubular agitator to stick to the inner surface of wall 47. Perforations 48 prevent the dispersing media from building up on said surface with the result that the dispersing media is continuously moving downwardly toward the bottom of the unit. The dispersing media at the bottom of the unit is mixed with fresh undispersed paste that has been fed through the top opening 42 and has also fallen to the bottom of the unit by gravity. Centrifugal force then causes the dispersing media and fresh paste to move outwardly and upwardly through the mixing zone rvand the process is repeated continuously .as fresh paste is constantly added and dispersed paste is constantly removed.

Apertures 48 may be omitted from tubular agitator 44 if desired, but the imperforate wall structure is less desirable than the perforated wall structure, because more -dispersing media sticks to the inner surface of the imperforate wall. The dispersing media on the inside of the cylinder does no substantial amount of work and therefore4 more sand is required to compensate for the extra sand that sticks to the inner wall surface of the imperforate tubular agitator.

Although I have described preferred embodiment of the invention in considerable detail, it will be understood that the description thereof islintended to be illustrative, rather than restrictive, as many details of construction ,may be modified or changed without departing from the close enough to cause the dispersing media to disperse the paste as said mixture is moved upwardly through said mixing zone, means to remove the dispersed paste from said mixture, and an inlet for the addition of undispersed paste to said previously used dispersing media after the dispersed paste has been removed from the mixture.

2. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a top, a tubular agitator having a vertical wall positioned within said container to form a mixing zone between the outer surface of the vertical wall of said agitator and the inner surface of said container, means for rotating said agitator to move said mixture through said mixing zone, the outer surface of the vertical wall of said agitator being sufficiently close to the inner surface of said container to cause said dispersing media to disperse said paste as said mixture moves through said mixing zone, means for separating the dispersed paste from said dispersing media adjacent the top of said container, the upper edge of the vertical wall of said agitator being spaced below said top to permit the used dispersing media to pass over it into the interior of said agitator after the dispersed paste has been separated from said dispersing media, and an inlet extending through said top for adding undispersed paste to the previously used dispersing media.

3. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a top, a tubular agitator having a vertical wall positioned within said container to form a mixing zone between the outer surface of the vertical wall of said agitator and the inner surface of said container, the vertical wall of said agitator having a plurality of apertures extending therethrough, means for rotating said agitator'to move said mixture through said mixing zone, the outer surface of the vertical wall of the agitator being sufficiently close to the inner surface of said container to cause said dispersing media to disperse said paste as said mixture moves through said mixing zone, means for separating the dispersed paste from said dispersing media adjacent-the top of said container, the upper edge of the vertical wall of said agitator being spaced below said top to lpermit the used dispersing media to pass over it into the interior of said agitator after the dispersed paste has beenV separated from said dispersing media, and an inlet extending through said top for adding undispersed paste to the previously used dispersing media.

4. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a top, a rotatable shaft extending into said container, a tubular agitator rigidly secured to said shaft, said agitator having a vertical wall positioned within said container and cooperating with said container to form a mixing zone between the outer surface of said vertical wall and the inner surface of, said container, means for rotating said shaft to move said mixture through said mixing zone, the outer surface of the vertical wall of said agitator being Asufficiently close to the inner surface of said container to cause said dispersing media to disperse said paste as said mixture moves through said mixing zone, a screened outlet adjacent the top of said container for separating the dispersed paste from said dispersing media, the upper edge of the vertical wall of said agitator being spaced below said top to permit the used dispersing media to pass over it into the interior of said agitator after the dispersed paste has been separated from said dispersing media, and an inlet extending through said top for adding undispersed paste to the previously used dispersing media. 4

5. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a top, a tubular agitator having a vertical wall positioned within said container and cooperating with said 4container to form a mixing zone between the outer surface of said vertical wall and the inner surface of said container, means for rotating said agitator to move said mixture through said mixing zone, the outer surface of the vertical Wall of said agitator being sufficiently close to the inner surface of said container to cause said dispersing media to disperse said paste as said mixture moves through said mixing zone, an outlet adjacent the top of said container for separating the dispersed paste from said dispersing media, a removable screen holder detachably secured to said container, a screen fixed to said holder and covering said outlet, the mesh of said screen being finer than said dispersing media, the upper edge of the vertical Wall of said agitator being `spaced below said top to permit the used dispersing media to pass over it into the interior of said agitator after the dispersed paste has been separated from said dispersing media, and an inlet extending through said top for adding undispersed paste to the previously used dispersing media.

6. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a closed bottom, a top and a vertical wall, an inlet extending through said top, an outlet adjacent the top of said container, a rotatable shaft extending into said container7 a tubular agitator comprising a substantially open bottom rigidly secured to said shaft above the bottom of said container and a vertical wall extending upwardly from said substantially open bottom, the vertical wall of said agitator being positioned Within said container and cooperating with said container to form a mixing zone between the outer surface of the vertical wall of said agitator and the inner surface of said container, and means for rotating said shaft to move a mixture of a dispersing media and paste upwardly through said mixing zone, the outer surface of the vertical wall of said agitator being sufficiently close to the inner surface of the vertical wall of said container to cause said dispersing media to disperse said paste as said mixture is moved through said mixing zone,

7. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a closed bottom, a top and a vertical wall,'an inlet extending -through said top, an outlet adjacent the top of said container, a screen covering said outlet, a rotatable shaft extending into said container, a tubular agitator comprising a substantially open bottom rigidly secured to said shaft above the lbottom of said container and a vertical wall, the vertical wall of said agitator being positioned within said container and cooperating with said container to form a mixing Vzone between the outer surface of the vertical wall of said agitator and the inner surface of said container, the upper edge of the vertical wall of said agitator being spaced 'below said top, means for rotating said shaft to move a mixture of a dispersing media and paste upwardly through said mixing zone, the outer surface of the vertical wall of said agitator being sufficiently close to the inner surface of the vertical wall of said container to cause said dispersing media to disperse said paste as said mixture is moved through said mixing zone, said screen having a mesh large enough to permit the dispersed paste to ow therethrough'and small enough to retain the dispersing media, whereby said dispersing media is forced over the upper edge of the vertical wall of said agitator by the upward movement of the mixture of paste and dispersing media beneath it, and means cooperating with lthe Vertical wall of said agitator to limit the amount of dispersing media caused to stick t-o its inner surface by centrifugal force as the dispersing media moves downwardly in said agitator.

8. An apparatus for dispersing paste in -a mixture of paste and dispersing media, said apparatus comprising a container having a closed bottom, a top and a vertical wall, an inlet extending through said top, and outlet adjacent the top of said container, a screen covering said outlet, a rotatable shaft extending into said container, a tubular agitator comprising a substantially open bottom rigidly secured t9 paid shaft above the bottom of said container and a vertical wall, the vertical wall of said agitator being positioned within said container and cooperating therewith to form a mixing zone `between the outer surface of the Vertical wall of said agitator and the inner surface of said container, the upper edge of the vertical w'all of said agitator being spaced below said top, and means for rotating said shaft to move a mixture of a dispersing media and paste upwardly through said mixing zone, the outer surface of the vertical wall of said agitator being sufficiently close to the inner surface of the vertical wall of said container to cause said dispersing media to disperse said paste as said mixture is moved through said mixing zone, said screen being tine enough to retain the dispersing media, whereby said dispersing media moves over the upper edge of the vertical wall of the agitator lby the movement of the mixture of paste and dispersing media beneath it, and down to the bottom of the container by gravity, the vertical wall of said agitator having perforations therein to limit the amount of dispersing media caused to adhere to its inner surface by centrifugal force as said dispersing media is moving downwardly through said agitator.v

9. An apparatus'for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a closed bottom and a top, an inlet extending through said top, an outlet adjacent the top of said container, a tubular agitator having a vertical wall of less length than said container positioned within said container, the outer surface of said vertical wall being spaced from the inner surface of said container to provide a mixing zone therebetween for dispersing media and paste, thevupper edge of the vertical wall of said agitator being spaced below said top, the lower edge of the vertical wall of said agitator being spaced above the bottom of said container, means for rotating said agitator to move said dispersing media and paste from the bottom of said container outwardly past the lower edge of the vertical wall lof said agitator and upwardly through said mixing zone to said outlet to cause the dispersing media to disperse said paste, and a screen covering said outlet, said screen being too fine to allow the dispersing media to pass therethrough, whereby the dispersed paste passes through said screen and the dispersing media is forced upwardly and inwardly over the upper edge of the cylindrical wall of said agitator 'by the upward movement of dispersing media and paste beneath it.

10. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus comprising a container having a closed bottom Iand a top, an inlet extending through said top, an outletadjacent 'the top of said container, a rotatable shaft extending into said container, a tubular agitator having a vertical wall ofless length than said container and a substantially open bottom rigidly connecting said vertical wall to said shaft, 4said vertical wall being positioned within said container with its outer surface spaced from the inner surface of said container to provide a mixing zone therebetween for dispersing media and paste, the upper edge of the vertical wall of said agitato-r being spaced `below said top, the lower edge of the vertical wall of said agitator being spaced above the bottom ofl said container, means for rotating said shaft to move said dispersing media and paste from the 'bottom of said container outwardly past the lower edge of the vertical wall of said agitator andupwardly through said mixing Zone to said outlet to cause the dispersing media to disperse said paste, and a screen covering said outlet, said screen being too ne to allow the dispersing media to pass therethrough, whereby the dispersed paste passes through said screen and the dispersing media is forced upwardly and inwardly over the upper edge of the vertical wall of said agitator by the upward movement of dispersing media and paste beneath it. t

1i. An apparatus for dispersing paste in a mixture of paste and dispersing media, said apparatus `comprising l of said container, a tubular agitator having a vertical wall of less length than said container positioned within said container, the outer surface of the vertical wall of said agitator being spaced from the inner surface of said container to provide a mixing Zone therebetween for the llow of a mixture of dispersing media and paste, the upper edge of the vertical wall of said agitator being spaced below said top, the lolweredge of the vertical wall of said agitator being spaced above the bottom of said container, means for rotating said agitator to move said dispersing media and paste from the bottom of said container outwardly past the lower edge of the vertical wall of said lagitator and upwardly through said passageway to said outlet to cause the dispersing media to disperse said paste, and a screen covering said outlet, said screen being too line to allow the dispersing media to pass therethrough whereby the paste passes through said screen and the dis-persing media is forced upwardly and inwardly over the upper edge of the vertical wall of said agitator by the upward movement of dispersing media and paste beneath it, the dispersing' rnedia moved over the upper edge of the vertical wall of said agitator falling to the bottom of said agitator vby gravity, the vertical wall of said agitator having perforations to limit the amount of dispersing media that can stick to the inner surface of the vertical wall of the agitator.

12. The process of dispersing paste which comprises adding undispersed paste to dispersing medi-a in the bottom of a container having a vertical wall, applying centrifugal force to said paste and dispersing media to move said paste and dispersing media outwardly to the vertical wall of said container and upwardly through an annular vertically dispersed mixing zone adjacent the vertical wall of said container, said centrifugal force causing said dispersing media to disperse said paste as said paste and dispersing media are moved upwardly through said mixing zone, separating said dispersed paste from said dispersing media adjacent the upper end of said mixing zone, returning said dispersing media to the bottom of said container, and adding fresh undispersed paste to said dispersing media in the bottom of said container to continue the process.

13. The process of dispersing paste which comprises adding undispersed paste to dispersing media in the bottom of a container having .a vertical wall,lrotating a tubular agitator having a vertical wall disposed in said container to apply centrifugal force to said paste and dispersing media to move said paste and dispersing media outwardly under the lower edge of said agitato-r to the vertical wall of said container and upwardly through an annular mixing zone defined by the outer surface of the vertical walls of said agitator and the inner surface of the vertical wall of said container, said centrifugal force -causing said dispersing media to disperse said paste as said paste and dispersing media are moved upwardly through said mixing zone, separating said dispersed paste from said dispersing media adjacent the upper end of said mixing zone, returning said dispersing media to the bottom of said container through said agitator, and dropping fresh undispersed paste through said agitator to add it to the dispersing medi-a in the bottom of said container to continue the process.

14. The process of dispersing paste which comprises adding undispersed paste to dispersing media in the bottom of a container having a vertical wall, rotating a tubular agitator having a vertical wall disposed in said container to apply centrifugal force to said paste and dispersing media to move said paste and dispersing media outwardly under the lower edge of said agitator to the vertical wall of said container and upwardly through an annular mixing zone defined by the vertical walls of said agitator and container, said contrifugal force causing said dispersing media to disperse said paste as said paste `and dispersing media are moved upwardly through said mixing zone, separating said dispersed paste from said dispersing media adjacent the upper end of said mixing zone, moving the dispersing media, from which said dispersed paste has been separated, upwardly from said mixing zone and inwardly over the upper edge of said agitator, by pressure of the paste and dispersing media being moved upwardly in said mixing chamber, returning said dispersing media to thebottorn of said container through said agitator, and dropping fresh undispersed paste through said `agitator to -add it to the dispersing media in the bottom of said container to continue the process.

References Cited by the Examiner UNITED STATES PATENTS Re. 16,759 10/ 1927 Snyder 241-73 574,282 12/ 1896 Sebastian 259-97 1,031,666 7/1912 Richmond 259-96 2,563,055 8/1951 Meyer et al. 259-107 X 2,855,156 10/1958 HOChberget al. 241-22 2,882,149 4/ 1959 Willems 259-96 X 2,890,028 6/1959 Lauffer.

f FOREIGN PATENTS 754,663 8/ 1956 Great Britain.

WALTER A. SCHEEL, Primary Examiner.

LEO QUACKENBUSH, Examiner. 

1. AN APPARATUS FOR DISPENSING PASTE IN A MIXTURE OF PASTE AND DISPERSING MEDIA, SAID APPARATUS COMPRISING AN INNER MEMBER AND AN OUTER MEMBER HAVING VERTICAL WALL SURFACES IN SPACED RELATIONSHIP FORMING A MIXING ZONE THEREBETWEEN, MEANS TO ROTATE SAID INNER MEMBER RELATIVE TO SAID OUTER MEMBER TO MOVE SAID MIXTURE UPWARDLY THROUGH SAID MIXING ZONE, SAID VERTICAL WALL SURFACES BEING CLOSE ENOUGH TO CAUSE THE DISPERSING MEDIA TO DISPERSE THE PASTE AS SAID MIXTURE IS MOVED UPWARDLY THROUGH SAID MIXING ZONE, MEANS TO REMOVE THE DISPERSED PASTE FROM SAID MIXTURE, AND AN INLET FOR THE ADDITION OF UNDISPERSED PASTE TO SAID PREVIOUSLY USED DISPERSING MEDIA AFTER THE DISPERSED PASTE HAS BEEN REMOVED FROM THE MIXTURE. 